Fire Watch: Utility Case Study
Contents
Transformer Swap Fire Watch: Utility Case Study
Utility substations look like steel and concrete fortresses, but inside they hold thousands of gallons of mineral oil and enough voltage to arc weld a crowbar. When a 138 kV transformer needs to be swapped, the foam suppression system is taken offline and the clock starts ticking. This case study shows how one utility saved six figures by treating the outage like a surgical fire watch mission.
The Project
A Midwest utility planned a three day outage to replace a 60 MVA transformer. The existing water-foam deluge system protected two adjacent transformers and a control room. Shutting the deluge meant a full impairment under NFPA 850 and state utility code.
Challenge
- 72 hour window, no foam coverage
- Hot oil welding on steel rails
- Adjacent energized transformers still online
- Remote location, 40 miles from nearest fire station
The Fire Watch Plan
We deployed four guards per 12 hour shift, two on the transformer deck and two on the control room roof. Each guard carried a 30 lb CO2 extinguisher and a 250 gpm portable monitor that could be fed from a nearby hydrant. Thermal drones flew every hour to scan for oil hotspots and arc flash signatures.
Key Moves That Saved Money
- Shared supervisor: One senior officer covered both day and night shifts, cutting supervisor cost in half
- Rental gear: Portable monitors were rented, not purchased, saving $18,000 in capex
- Drone patrol: Replaced one human guard per shift, saving $4,800 in labor
- Staggered welding: Hot work was limited to daylight hours, reducing night shift premium
The Spark That Didn’t Become a Fire
At 2:17 p.m. on day two, a welding slag ball rolled into a pool of residual oil. The deck guard hit it with CO2 within 15 seconds and radioed for the monitor. Thermal drone showed 180°F at the spot. We soaked the area for ten minutes, logged the event and resumed work. Total delay: 22 minutes. Without immediate watch, that slag would have ignited the oil and triggered a transformer explosion.
Final Numbers
Total fire watch cost: $52,400. Estimated loss if a fire occurred: $12 million in equipment plus six months of lost transmission revenue. ROI: 229 to 1. The utility now includes our fire watch line item in every major outage budget.
Takeaway for Any Industrial Site
Treat high voltage and high oil the same as high explosive. Post enough guards to hit the fire in the first sixty seconds and give them the tools to fight until the fire department arrives. Anything less is a donation to the insurance company.
Planning a transformer swap, turbine outage or reactor maintenance? Contact us and we will build a utility grade fire watch plan that keeps the power on and the claims off.
